Method for producing semiconductor layers and coated substrates treated with elemental selenium and/or sulfer, in particular flat substrates

ABSTRACT

The invention relates to a method for producing semiconductor layers and coated substrates treated with elemental selenium and/or sulphur, in particular flat substrates, containing at least one conducting, semiconducting and/or insulating layer, in which a substrate which is provided with at least one metal layer and/or with at least one layer containing metal, in particular a stack of substrates, each of which is provided with at least one metal layer and/or with at least one layer which contains metal, is inserted into a processing chamber and heated to a predetermined substrate temperature; elementary selenium and/or sulphur vapor is guided past on the or on every metal layer and/or layer containing metal, from a source located inside and/or outside the processing chamber, in particular by means of a carrier gas which is in particular inert, under rough vacuum conditions or ambient pressure conditions or overpressure conditions, in order to react chemically with said layer with selenium or sulphur in a targeted manner; the substrate is heated by means of forced convection by at least one gas conveying device and/or the elementary selenium and/or sulphur vapor is mixed and guided past on the substrate by means of forced convection by at least one gas conveying device in the processing chamber, in particular in a homogeneous manner. The invention furthermore relates to a processing device for implementing a method of this type.

The invention relates to a method for producing semiconductor layers andcoated substrates treated with elemental selenium and/or sulphur, inparticular flat substrates, containing at least one conducting,semiconducting and/or insulating layer, in which a substrate which isprovided with at least one metal layer and/or with at least one layercontaining metal, in particular a stack of substrates, each of which isprovided with at least one metal layer and/or with at least one layerwhich contains metal, is inserted into a processing chamber and heatedto a predetermined substrate temperature.

A method of this type is known in general and is used for example in thesolar cell industry in the production of CIS solar cells. In particular,a known method of this type for producing I-III-VI connectionsemiconductor layers, the chalcopyrite semiconductor layers, is used.For this purpose, for example, substrates comprising a molybdenum thinlayer, such as glass substrates, are respectively provided with aprecursor thin metal layer comprising copper, gallium and indium andthen heated in the processing chamber according to a predeterminedtemperature profile while being subjected to a feed of H₂Se and H₂S. Inone variant, substrates comprising a molybdenum thin layer arerespectively provided with a precursor thin metal layer comprisingcopper, gallium, indium and selenium, and then heated in the processingchamber according to a predetermined temperature profile while beingsubjected to a feed of H₂S. Due to a reaction of the precursor metallayers with the selenium containing H₂Se and the sulphur contained inthe H₂S, Cu(In,Ga)(Se,S)₂ semiconductor layers, or chalcopyritesemiconductor layers, are formed on the substrates. This process is alsoknown as selenization or sulphurization.

The use of H₂Se and H₂S is problematic in the sense that H₂Se and H₂Sare not only expensive to procure, but are also toxic and highlyexplosive gases. These gases are therefore a significant economic factorin the mass production of CIS solar cells, not only due to theirprocurement costs, but also as a result of the increased safety measuresand the costs entailed in disposing of the related discharge gases. Thisaside, due to their toxicity and explosivity, the safety risk presentedby these gases for production staff should not be underestimated, evenwhen preventive measures are taken.

The object of the invention is to provide a safer and more economicmethod for producing a semiconductor layer, in particular a chalcopyritesemiconductor layer, or a buffer layer on a semiconductor layer.

In order to attain the object, a method for producing semiconductorlayers and coated substrates treated with elemental selenium and/orsulphur, in particular flat substrates, containing at least oneconducting, semiconducting and/or insulating layer is provided, in whicha substrate which is provided with at least one metal layer and/or withat least one layer containing metal, in particular a stack ofsubstrates, each of which is provided with at least one metal layerand/or with at least one layer which contains metal, is inserted into aprocessing chamber and heated to a predetermined substrate temperature;

elementary selenium and/or sulphur vapor is guided past on the or onevery metal layer and/or layer containing metal, from a source locatedinside and/or outside the processing chamber (internal or externalsource), in particular by means of a carrier gas which is in particularinert, under rough vacuum conditions or ambient pressure conditions oroverpressure conditions, in order to react chemically with said layerwith selenium or sulphur in a targeted manner;

the substrate is heated by means of forced convection by at least onegas conveying device and/or the elementary selenium and/or sulphur vaporis mixed and guided past on the substrate by means of forced convectionby at least one gas conveying device in the processing chamber, inparticular in a homogeneous manner.

In the spirit of the present invention, the metal layer and/or layercontaining metal to be treated with selenium and/or sulphur are alsoreferred to below as the precursor layer. The metal layer contains inparticular one element or several elements selected from aluminium,silver, zinc, magnesium, molybdenum, copper, gallium and indium, whereincopper, gallium and/or indium are preferred.

In the spirit of the present invention, the layer which contains metalcomprises i) at least one metal, e.g. In, Zn and/or Mg, and anon-metallic element of the periodic table of elements, in particularsulphur and/or selenium and if appropriate, chlorine, oxygen orhydrogen, and/or ii) at least one chemical compound of a metal, e.g. In,Zn and/or Mg, with a non-metallic element of the periodic table ofelements, in particular sulphur and/or selenium and if appropriate,chlorine, oxygen or hydrogen. The layer containing metal thus alsocomprises those embodiments in which alongside at least one metal, atleast one chemical compound of a metal and/or a non-metallic element arealso present. Furthermore, the layer containing metal also comprises inthe spirit of the present invention those layers in which no pure metalis present, but solely at least one chemical compound of a metal, ifappropriate together with non-metallic elements and/or compounds.

With the method according to the invention, at least one substrate whichis provided with a precursor layer and in particular a stack ofsubstrates which are in each case provided with a precursor layer isinserted into a processing chamber and heated to a predeterminedsubstrate temperature. The method according to the invention ischaracterized by the fact that elementary selenium and/or sulphur vaporis guided past from a first or second source located inside and/oroutside the processing chamber by means of a carrier gas which is inparticular inert under rough vacuum conditions to overpressureconditions on the or on each precursor layer, in order for said layer toreact chemically in a targeted manner with selenium or sulphur. In thiscontext, process conditions are designated as rough vacuum conditions inwhich processing pressures ranging from ambient pressure to 1 mbar arepresent. The method according to the invention and the device accordingto the invention can in general also be used with overpressure, however.

According to the invention, the selenium required to react with theprecursor layer or the sulphur required to react with the precursorlayer is thus not provided by H₂Se or H₂S gas, but by elementaryselenium or sulphur vapor, i.e. vapor containing elementary selenium orvapor containing elementary sulphur. According to the invention,therefore, the use of H₂Se and H₂S is not required. The method accordingto the invention can nevertheless permit the use of H₂Se and/or H₂S,during or after the selenization stage with elementary selenium vapor orbefore, during or after the sulphurization stage with elementary sulphurvapor. In particular, in one embodiment of the method according to theinvention, H₂Se and/or H₂S can be added before and/or during theselenization stage with elementary selenium, in particular attemperatures ranging from room temperature to 350° C., preferably attemperatures ranging from 100° C. to 300° C.

In contrast to H₂Se and H₂S, elementary selenium vapor and elementarysulphur vapor are neither highly toxic, nor explosive, and are thussignificantly less hazardous to handle, so that no complex and costlysafety measures are required. Furthermore, elementary selenium vapor andelementary sulphur vapor are easy to obtain e.g. from a melted seleniumor sulphur mass. As a result, the method according to the invention canbe conducted at a significantly lower economic cost and with a farhigher degree of safety.

Advantageous embodiments of the method are described in the subclaims,the description and the drawings.

In one embodiment, it is provided that the gas conveying device is aninjection nozzle or a ventilator. Furthermore, it can be provided thatthe gas conveying device, in particular the ventilator, is preferablyarranged in the area of one of the front sides of the processing goodsstack, and/or is affixed to a drive shaft which extends into theprocessing chamber.

In order to attain the required vapor pressure of the selenium orsulphur vapor, in particular the first source is preferably maintainedat an increased source temperature. Here, the source temperature ispreferably lower than the temperature in the processing chamber, and inparticular, lower than a minimum substrate temperature at any point intime during the guiding past of the elementary selenium and/or sulphurvapor on the substrate. As a result, it applies for every substratetemperature in the processing chamber that the partial pressure of theselenium or sulphur is lower than the vapor pressure of the selenium orsulphur with the respective substrate temperature. Thus, a condensationof the selenium or sulphur vapor on the substrate is avoided, which isan important requirement for a homogeneous reaction to a semiconductorlayer. Condensation of selenium vapor on the substrate, for example,would lead to drying of the selenium and thus result in a lateral,inhomogeneous layer thickness distribution of the selenium and alateral, inhomogeneous reaction procedure.

According to the invention, the substrate is heated using forcedconvection and/or the selenium or sulphur vapor is guided past on thesubstrate by means of forced convection. When the substrate is heated bymeans of forced convection, the temperature distribution is particularlyhomogeneous across the substrate. In other words, temperaturefluctuations are minimized across the substrate.

When elementary selenium or sulphur vapor is guided past on thesubstrate by means of forced convection, a particularly homogeneousprogress of the reaction of the selenium or sulphur with the precursorlayer is achieved across the surface of the substrate.

According to a further embodiment, a feed line through which theelementary selenium or sulphur vapor is guided on the route from thefirst source to the substrate, and/or a wall which defines theprocessing chamber is maintained at a temperature which is equal to orgreater than the source temperature. This ensures that the selenium orsulphur vapor does not condense on the feed line or on the processingchamber wall, but solely reacts chemically in a targeted manner with theprecursor layer located on the substrate.

A bubbler comprising fluid selenium or fluid sulphur through which thecarrier gas is guided can be used as a source, or a crucible filled withfluid selenium or sulphur can be used which comprises a side whichenables the selenium or sulphur to evaporate, and on which the carriergas is guided past. A source of this type is not only characterized by asimple and cost-effective structure, but can also be integrated intoalready existent processing plants, so that existing processing plantscan be upgraded in a simple manner in order to implement the methodaccording to the invention. Sources of this type can be located bothinside the processing chamber and outside the processing chamber.Suitable sources in the spirit of the present invention also take theform of elementary selenium and/or elementary sulphur inserted in solidform into the processing chamber, for example in the form of pellets orpowder. In this case, a feed line or feed device is required in theprocessing chamber, with which the elementary selenium which is providedin solid form or the elementary sulphur which is provided in solid formcan be transferred, preferably under inert conditions such as withprotective gas (argon, nitrogen etc.), for example into one or morecrucibles which are attached in the processing chamber. These cruciblesare preferably heatable in a controlled manner, and it is preferablypossible that protection gas from a controllable flow and a controllabletemperature can flow through or against them, so that the vaporizationrate can be influenced in a targeted manner, and by measuring theselenium or sulphur partial pressure, said pressure can be preciselycontrolled and adjusted in the processing chamber. Accordingly, it canbe provided that selenium and/or sulphur is inserted in solid form via atransfer device into the processing chamber, wherein said transferdevice can take the form of a second feed line or a sluice chamber.Here, a procedure is advantageous in which pre-heated carrier gas is fedvia the second and/or at least one third feed line to the internalselenium and/or sulphur source.

In one embodiment, accordingly the solid selenium and/or the solidsulphur is or are converted into the vapor phase by means of the heatingdevice located in the processing chamber, with the aid of the forcedconvection. In a further embodiment, an exchangeable crucible, known asa shuttle, is fed outside the processing chamber with the elementaryselenium which is provided in solid form or with the elementary sulphurwhich is provided in solid form, and is transferred to the processingchamber, preferably under inert conditions, for example under protectivegas (argon, nitrogen etc.), e.g. with the aid of the forenamed transferdevice or sluice chamber. These crucibles are also preferably heatablein a controlled manner, and it is preferably possible that protectiongas from a controllable flow and a controllable temperature can flowthrough or against them, so that the vaporization rate can be influencedin a targeted manner, and by measuring the selenium or sulphur partialpressure, said pressure can be precisely controlled and adjusted in theprocessing chamber. Advantageously, the chemical reaction of theselenium and/or the sulphur with the precursor layer, i.e. theselenization or sulphurization, is conducted with a pressure in theprocessing chamber ranging from approximately 1 mbar to approximately1,030 mbar. These processing pressures are on the one hand so low thatthe process gases, in particular, the selenium vapor or sulphur vapor,cannot escape from the processing chamber. At the same time, theseprocess pressures are so high, however, that these processes are nothigh or fine vacuum processes in the real sense. Thus, lowerrequirements are necessary for the vacuum technology and in particularthe pump capacity of existing pumps, as a result of which the methodoverall can be implemented even more cost-effectively.

Both the selenium and the sulphur vapor pressure can lie within a rangeof 1e-7 mbar and 1,000 mbar, depending on the processing temperature.Typically, the selenium or sulphur partial pressure lies within a rangeof approximately 0.001 mbar and approximately 100 mbar.

According to a special embodiment of the method according to theinvention, which is particularly suitable for producing a I-III-VIconnection semiconductor layer and chalcopyrite semiconductor layer, themethod comprises the following stages:

-   -   Increase of the substrate temperature with a heating rate of        approximately 5° C./min to 600° C./min, preferably 10° C./min to        60° C./10 mins, from a first temperature, in particular room        temperature, to a temperature ranging from approximately 400° C.        to 600° C., preferably 400° C. to 500° C.    -   Feeding of elementary selenium vapor into the processing chamber        from a substrate temperature ranging from 100° C. to 350° C., in        particular between 120° C. and 300° C., if appropriate, followed        by the feeding of elementary sulphur vapor into the processing        chamber, and here if appropriate, the subsequent adjustment of        the selenium source temperature to a required partial pressure,        preferably between 0.001 mbar and 100 mbar    -   Maintenance of the substrate temperature in a range from 400° C.        to 600° C. for 1 min to 120 mins, preferably for 10 mins to 30        mins    -   While maintaining the substrate temperature in a range from        400° C. to 600° C., shutdown of the feed of elementary selenium        vapor, and if appropriate, of sulphur vapor into the processing        chamber after a first predetermined time period, in particular        after a time period of between 1 and 120 mins, preferably        between 1 and 60 mins    -   At least a one-time pumping out and/or rinsing of the processing        chamber, in particular with at least one inert gas    -   Feeding of elementary sulphur vapor into the processing chamber    -   Continued increase of the substrate temperature with a heating        rate of approximately 50° C./min to 600° C./min, preferably 10°        C./min to 60° C./min, to a temperature ranging from        approximately 450° C. to 650° C., preferably 500° C. to 550° C.,        and during this procedure, if appropriate, an adjustment of the        sulphur source temperature to a required partial pressure,        preferably between 0.001 mbar and 100 mbar    -   Maintenance of the substrate temperature in a range from 450° C.        to 650° C. for 1 min to 120 mins, preferably for 1 to 60 mins,        and particularly preferably for 10 mins to 30 mins    -   While maintaining the substrate temperature in a range from        450° C. to 650° C., shutdown of the feed of elementary sulphur        vapor into the processing chamber after a second predetermined        time period, in particular after a time period of between 1 and        120 mins, preferably between 1 and 60 mins    -   Cooling of the substrate, and    -   Pumping out and/or rinsing of the processing chamber, in        particular with at least one inert gas

Furthermore, it can be provided that in a first stage, elementaryselenium vapor is guided past on the or each precursor layer(selenization stage), and that in a subsequent stage, elementary sulphuris guided past on the or each precursor layer (sulphurization stage).

Advantageously, already during the selenization stage, e.g. from asubstrate temperature of between 120° C. and 600° C., elementary sulphurvapor is fed into the processing chamber, in particular in such a mannerthat a partial pressure ratio of selenium to sulphur is created between0 and 0.9, or preferably of sulphur to selenium ranging from above 0 to0.9, preferably between 0.1 and 0.3.

Furthermore, in one embodiment with the method according to theinvention, coated, in particular planar substrates, in particularpre-coated glass substrates, can be used for the production ofsemiconductor layers, preferably chalcopyrite semiconductor layers,preferably I-III-VI connection semiconductor layers and in particularCu(In, Ga)(Se,S)₂ semiconductor layers, for example for solar cells.

Although to date, the method according to the invention has beendescribed primarily in connection with the selenization orsulphurization of a precursor layer for the production of a chalcopyritesemiconductor layer, it should be noted that the method according to theinvention is also suitable for the production of other semiconductorlayers. Thus, the semiconductor layer to be produced can also be abuffer layer, for example an In₂S₃ layer or a layer comprising a phasemixture of indium sulphides and indium selenides, e.g. In(S,Se)₃. Inthese cases, the precursor layer would comprise indium and/or a compoundof indium and one or more elements, selected from oxygen and/orchlorine, and in particular, sulphur and/or selenium. This precursorlayer can for example be obtained using thin layer separation methodsand PVD methods known to persons skilled in the art, such as cathodesputtering, evaporating or CVD methods. Specifically, a thin layer forindium or an indium-sulphur compound can be separated on a I-II-Vsemiconductor layer formed on molybdenum, in order that duringsulphurization, an In₂S₃ semiconductor buffer layer, or duringsulphurization and selenization, in this order or in reverse order orsimultaneously, an In₂(S,Se)₃ layer is formed on the I-III-Vsemiconductor. Accordingly, however, it is also possible that theprecursor layer contains one or more elements, selected from In, Zn orMg, as a result of which accordingly ZnS or MgS layers or mixed formscan be formed for example, which can for example contain indium sulphideand zinc sulphide.

When producing a buffer layer which lies on a I-III-V semiconductorlayer with the method according to the invention, substrate temperaturesshould regularly be selected which lie below those used during theformation of I-III-V semiconductor layers in accordance with the methodaccording to the invention. As a result, an unwanted modification of thesurface of the I-III-V semiconductor layer can be avoided. Preferably,the substrate temperatures are here limited to levels lower than orequal to 350° C., preferably to lower than or equal to 250° C.Furthermore, it is preferred when for the production of the bufferlayer, temperatures greater than 150° C., preferably greater than orequal to 160° C. are selected.

It generally applies to selenium and sulphur source temperatures thatthese are preferably maintained lower than or equal to the substratetemperature during each phase of the method. In this case, the maximumachievable vapor pressures with the corresponding maximum processtemperatures can be taken from the sulphur and selenium vapor pressurecurves.

Depending on the process implementation or the semiconductor layer to beproduced, it can here be advantageous when at least one reactive gas,such as hydrogen, H₂Se or H₂S in particular, is furthermore added.

A further object of the invention is a processing device forimplementing the method according to the invention, comprising anevacuable processing chamber for receiving at least one substrate to beprocessed, in particular a stack of substrates to be processed a heatingdevice for the in particular convective heating of the substrate to beprocessed a first source for elementary selenium and/or sulphur vaporlocated outside the processing chamber and which is connected to theprocessing chamber via a first feed line and/or a second source forelementary selenium and/or sulphur vapor located inside the processingchamber, and a gas conveying device for generating a gas flow circuit,in particular by means of forced convection in the processing chamber.

The processing device according to the invention comprises in anembodiment as a gas conveying device an injection nozzle or aventilator. Here, it can preferably be provided that the gas conveyingdevice, in particular at least one ventilator, is arranged orarrangeable in the area of one of the front sides of the substratestack.

The processing device according to the invention is in one preferredembodiment furthermore equipped with at least one tempering device, inorder to maintain at a predetermined temperature at least one partialsection of a wall which defines the processing chamber, in particularthe entire wall, and if appropriate, at least one section of the feedline respectively.

The processing device according to the invention comprises an evacuableprocessing chamber for receiving at least one substrate to be processedand in particular, a stack of substrates to be processed, a heatingdevice for the in particular convective heating of the substrate to beprocessed, a first source for elementary selenium and/or sulphur vaporwhich is located outside the processing chamber and which is connectedto the processing chamber via a feed line, and/or a second source forselenium and/or sulphur vapor located inside the processing chamber, ifappropriate, a tempering device, in order to maintain at a predeterminedtemperature at least a partial section of a wall which defines theprocessing chamber and at least one section of the feed linerespectively, and at least one gas conveying device in order to achieveenforced convection.

Due to the tempering device, the processing chamber wall and the feedline can be maintained at a temperature at which the material of theprocessing chamber wall or the feed line does not corrode under theinfluence of the processing gas atmosphere. For example, it is knownthat a corrosive attack increases significantly with the temperature,and at temperatures in the range below 250° C., stainless steel hardlycorrodes at all in a noticeable manner in a processing gas atmospherecontaining selenium or sulphur. Due to the known vapor pressure curvesfor selenium and sulphur, it cannot be anticipated that selenium orsulphur condenses under the processing conditions on the tempered andthermally insulated walls of the processing chamber. Due to thetempering, the processing chamber is to be classified in terms of typeas a heating wall reactor, which is stable in the long term and whichemits no particles which damage the process. Furthermore, due to thetempering it is ensured that the process can be controlled very well,since in general, components of the processing gas which are in vapor orgas form and in particular, selenium or sulphur, are neither condensedout in an uncontrollable manner during the processing sequence, nor arethey fed back into the process in an uncontrollable manner.

The processing chamber can be formed from a metallic material. Thismeans that the processing chamber can produce not only at the sameprocessing capacity, but above all also with a larger chamber volume ata lower cost than a quartz tube, for example. While quartz tubediffusion ovens can only be produced with a diameter of up to 80 cm, aprocessing chamber formed from a metallic material can be comparativelyeasily adapted to larger processing goods formats, i.e. substratesurfaces, by increasing the height and width accordingly.

Advantageously, on the inner side of the processing chamber wall, athermal insulation material is provided which preferably maintains aconsistent reaction under processing conditions. On the one hand, theinsulation material forms an additional protection for the processingchamber wall, e.g. against corrosion, and on the other, achieves acertain thermal decoupling of the processing chamber wall from the gasatmosphere in the processing chamber, so that the temperature of the gasatmosphere can be regulated more precisely. The thermal decoupling isessentially based on the lower specific heat capacity, the lower thermalconductivity and the emissivity, which in some cases is also lower, asis typical for insulation materials. Additionally, the thermalinsulation material prevents the processing chamber wall from beingheated above the predetermined temperature by the hot processing gas, orthe heat discharge from becoming too great. The thermal insulationmaterial is particularly advantageous with forced convection by the gasconveying device, since in this manner, the heat discharge issignificantly contained due to an otherwise good heat transfer.

The insulation material can for example be a ceramic, a glass ceramic,graphite, including graphite foam or fibre, e.g. Carbon Fibre EnforcedCarbon (CFC) or graphite felt, or an insulation material containingceramic fibres, e.g. consisting of SiO₂ and Al₂O₃ fibres.

According to one embodiment of the processing device, the sourcecomprises a heatable and evacuable source chamber, in which a crucibleis arranged with is filled with melted selenium or sulphur mass, and aline for in particular pre-heated carrier gas, in such a manner that thecarrier gas is either guided through according to the bubbler principlethrough the melted selenium or sulphur mass, or is guided away over asurface of the melted selenium or sulphur mass. The heatable crucibleand the heatable line preferably comprise a material which remainsstable in selenium or sulphur, and are formed e.g. of ceramic, quartz orcorrosion-resistant special alloys.

In the processing chamber of the device according to the invention, agas conveying device is furthermore provided to generate a gas flowcircuit in the processing chamber. The gas conveying device preferablycomprises at least one ventilator. The ventilator can be an axial orradial fan, for example.

The ventilator can comprise a material which remains stable, and can beattached to a drive shaft which extends into the processing chamber andwhich preferably also comprises a material which remains stable. Due tothe use of the material which remains stable, the ventilator and/or thedrive shaft are protected against attack by reactive components of theprocessing gas, and in particular are protected against corrosion.

Advantageously, the ventilator is arranged in the area of one of thefront sides of the substrate stack. This arrangement of the ventilatorscontributes towards a particularly homogeneous through flow of asubstrate stack with processing gas, and thus to a particularlyhomogeneous deposition of the layers and layer reaction.

In order to further increase the flow speed and the homogeneity of thegas flow, an additional ventilator is advantageously arranged in thearea of the other front side of the substrate stack. With thisarrangement of two ventilators, preferably the one ventilator isdesigned in such a manner that it conveys the processing gas into thesubstrate stack, while the other ventilator conveys the processing gasout of the substrate stack. In other words, the one ventilator operatesin “impulse mode,” while the other operates in suction mode.

The ventilator or drive shaft material which remains stable can forexample be a ceramic material such as silicon nitride or siliconcarbide.

Preferably, the drive of the ventilator, or the drives of theventilators, can also operate in the inverse direction of rotation, sothat the gas flow circuit can be reversed. As an option, radialventilators can be attached to both sides of the substrate stack, withwhich the gas flow direction can be reversed by switching on thepreviously shut down ventilator, and shutting down the ventilator whichwas previously switched on.

According to yet another embodiment, the heating device is arranged inthe gas flow circuit generated by the gas conveying device, in order toheat up a gas located in the processing chamber, in particular thecarrier gas which is displaced by the elementary selenium or sulphurvapor. In other words, the heating device is arranged inside theprocessing chamber, so that a heat source located outside the processingchamber, such as an infrared radiation source, is no longer required inorder to heat the processing gas. Thus, it is not necessary to optimizethe processing chamber with regard to infrared radiation, rendering thestructure of the processing significantly more simple, as well asenabling the use of a metallic material to produce the processingchamber.

The heating device can comprise at least one corrosion-resistant heatingelement. In particular, the heating device can be designed as a platestack of resistance heating elements. For example, graphite or siliconcarbide heating elements can be used here as plate-type meander heatersor as heating rods. Depending on the design of the gas flow speed, theheating capacity and the surface of the heating matrix, heating rates ofthe goods to be processed can be achieved ranging from several degreesCelsius per minute to several degrees Celsius per second.

According to yet another embodiment, a cooling device is arranged in thegas flow circuit generated by the gas conveying device, in order to cooldown a gas located in the processing chamber, in particular the carriergas which is displaced by the elementary selenium or sulphur vapor.

The cooling device can comprise at least one cooling element and inparticular, a plate stack cooler or tube bundle cooler. The coolingelement can for example be maintained at a temperature of e.g.approximately 200° C. by means of an oil tempering device. Depending onthe gas flow speed, the cooler capacity and the surface of the coolerarrangement, cooling rates can be achieved on the goods to be processedof up to several degrees Celsius, in particular up to several tens ofdegrees Celsius per minute.

According to yet another embodiment, gas diversion elements areprovided, via which the gas flow circuit can be diverted in such amanner that either the heating device or a cooling device is arranged inthe gas flow circuit. When set accordingly, the gas diversion elementsenable a particularly rapid heating or cooling of the goods to beprocessed to a required temperature, and thus ultimately enable therealization of almost any temperature profiles required in theprocessing chamber.

In addition to the gas conveying device, the processing device cancomprise a gas guidance device which retains a substrate staple andwhich is arranged in the processing chamber in such a manner that atleast one part of the gas flow circuit generated runs through the gasguidance device. The gas conveying device and the gas guidance deviceprovide on the one hand a particularly homogeneous heating and coolingof the substrate stack via forced convection, and on the other, providea particularly homogeneous gas distribution and as a result, ultimatelya particularly homogeneous layer formation, e.g. of a chalcopyritesemiconductor, on the substrates.

The combination of the gas conveying device, the gas guidance device andthe heating device enables an increase in heating and cooling speed, asa result of which shorter processing times and thus a higher throughputof goods to be processed are possible.

The gas guidance device can comprise at least one upper separation platewhich defines a first chamber area in the processing chamber above thegas guidance device which retains the substrate stack, and a lowerseparation plate which defines a second chamber area in the processingchamber below the gas guidance device which retains the substrate stack.Additionally, the gas guidance device can also comprise two sideseparation plates.

Preferably, the gas guidance device comprises at least one distributiondevice for the even surface distribution of the gas flow, wherein thesubstrate stack is preferably arranged upstream of the distributiondevice. The distribution device can for example be a plate which isequipped with slits and/or holes. The distribution device and the gasguidance device preferably consist of a material which remains stable,e.g. a glass ceramic, silicon carbide, quartz or silicon nitride. In asimilar manner to the processing chamber wall, the surfaces of the gasguidance device can also be equipped with a thermal insulation materialwhich is preferably stable under processing conditions. In this manner,the gas guidance device is also at least to a large extent thermallydecoupled from the gas atmosphere in the processing chamber, so that theprocessing device, in particular in the dynamic case of a settemperature change, comprises a lower thermal mass overall, as a resultof which the temperature of the processing gas in the processing chambercan be regulated even faster and more precisely. Due to its stabilityagainst reactive components of the processing gas, the insulationmaterial also forms an additional protection for the gas guidancedevice, e.g. against corrosion.

In one embodiment of the device according to the invention, it isprovided that the first source comprises a heatable and evacuable sourcechamber, in which a crucible filled with melted selenium or sulphur massis arranged or arrangeable, and a line for in particular pre-heatedcarrier gas, in such a manner that the carrier gas is either guidedthrough or can be guided through the melted selenium or sulphur massaccording to the bubbler principle, or is guided away from or can beguided away from the melted selenium or sulphur mass, wherein thecrucible and the line preferably comprise material which remains stablein selenium or sulphur, and in particular are formed from ceramic,quartz or corrosion-resistant special alloys or metals withcorrosion-resistant coatings.

Furthermore, it can be provided that the heating device is arranged orarrangeable in the gas flow circuit generated by the gas conveyingdevice, in order to heat a gas located in the processing chamber; and/ora cooling device for cooling down a gas located in the processingchamber is arranged or arrangeable in the gas flow circuit generated bythe gas conveying device; and/or gas diversion elements are providedthrough which the gas flow circuit can be diverted in such a manner thateither the heating device or a cooling device is arranged or arrangeablein the gas flow circuit.

In a preferred embodiment, devices according to the invention canfurthermore be characterized by at least one device for the transferinto the processing chamber of solid selenium and/or solid sulphur whichare in particular dosed in advance. Here, it can be provided that thetransfer device comprises a second feed line and/or a sluice chamber, inparticular containing a retaining device for solid selenium or solidsulphur.

A further object of the invention is additionally a processing plant forprocessing stacked substrates with at least one processing device,wherein the processing device comprises a loading opening, through whichthe substrate stack can be inserted into the processing chamber, and adischarge opening, through which the substrate stack can be removed fromthe processing chamber.

Advantageously, the processing plant comprises a further processingdevice which is arranged adjacent relative to the one processing device,and comprises a loading opening which is aligned with the dischargeopening of the one processing device. The loading opening and/or thedischarge opening can here be closed by a door, in particular a platevalve.

Preferably, the additional processing device is a cooling device whichcomprises a cooling facility, and which is arranged in a gas flowcircuit which is generated by a gas conveying device in an evacuableprocessing chamber of the cooling device. Additionally, the processingplant can comprise a sluice chamber which is upstream of the firstprocessing device in terms of the through-flow direction, with orwithout convective pre-heating.

Due to the adjacent arrangement of several processing devices, theprocessing plant forms a through-flow plant for the stack of goods to beprocessed. To a certain extent, it is therefore a batch inline plan,which combines the advantages of continuous through-flow operation withthose of batch operation.

It is a matter of course that the number of processing devices is notlimited to two. To a far greater extent, the processing plant can forexample comprise a number n of processing devices and a number m ofcooling devices, wherein n and m are natural numbers, and wherein forthe simplest variant, only a batch-inline combination processing plantn=m=1 applies.

The invention will now be described below in purely exemplary form withreference to an advantageous embodiment and with reference to theappended drawings, in which:

FIG. 1 shows a schematic view of a processing device according to theinvention;

FIG. 2 shows vapor pressure curves of selenium and sulphur as a functionof the source temperature;

FIG. 3 shows the time progression of the substrate temperature and thesource temperature during a method implemented in the device shown inFIG. 1 for producing a chalcopyrite semiconductor;

FIG. 4 shows a schematic longitudinal view of the processing devicealong the line A-A shown in FIG. 1;

FIG. 5 shows a schematic longitudinal view of a processing plant with aprocessing device of the type shown in FIG. 1 and a cooling device shownadjacent to it; and

FIG. 6 shows a schematic longitudinal view of an alternative embodimentof a processing plant with a sluice chamber upstream of the processingdevice and a cooling device downstream of the processing device;

FIG. 7 shows a schematic view of an alternative embodiment of aprocessing device according to the invention;

FIG. 8 shows a schematic view of a further alternative embodiment of aprocessing device according to the invention; and

FIG. 9 shows a detailed view of a section of the device according to theinvention shown in FIG. 9 in a schematic transverse view.

FIG. 1 shows a processing device 10 according to the invention, which isprovided for the formation of Cu(In, Ga)(Se, S)₂ semiconductor layers onsubstrates 12 which are to be used for the production of solar cells.

The processing device 10 comprises an evacuable processing chamber 14,which is limited by a processing chamber wall 16. The processing chamberwall 16 is formed from stainless steel and is maintained by a temperingdevice 18 at a temperature ranging from 150° C. to 250° C.

In the present exemplary embodiment, the tempering device 18 is formedby tube lines 20 which are attached to the outer side of the processingchamber 14, and in particular are welded to the processing chamber wall16 and which encircle the processing chamber 14 in a meander form,through which a suitable hot oil flows. As an alternative oradditionally, the hot oil can however also flow through channels (notshown) which are accordingly embedded into the processing wall 16.Additionally, the outer side of the processing chamber wall 16 can beequipped with a thermally insulating material.

On an inner side of the processing chamber wall 16, the processingchamber 14 is at least approximately completely cladded with acorrosion-resistant, low-particle, thermal insulation material 22. Theinsulation material 22 can be a ceramic, a glass ceramic, graphite orgraphite foam, including a fibre material, e.g. Carbon Fibre EnforcedCarbon (CFC) or graphite felt, or an insulation material containingceramic fibres, e.g. consisting of SiO₂ and Al₂O₃ fibres.

A gas guidance device 24 is arranged in a central area of the processingchamber 14. The gas guidance device 24 comprises an upper separatingplate 26 and a lower separating plate 28. In addition to the upper andlower separating plate 26, 28, a front and a rear separating plate (notshown) can be provided. Generally, however, the front and rearseparating plate are not present, since their function is fulfilled bythe thermally insulated chamber side walls, including the doors orvacuum valves arranged there. The upper and lower separating plate 26,28 and if appropriate, the front and rear separating plate arepreferably formed from a corrosion-resistant material, such as CFC, froma ceramic material, such as silicon carbide or silicon nitride, or aglass ceramic material.

All separating plates are also cladded with a layer of the forenamedthermal insulation material 22.

The gas guidance device 24 furthermore comprises a first distributordevice 30, which is arranged in the area of a first (in FIG. 1 on theleft) front side of the gas guidance device 24 between the separatingplates 26, 28, and/or a second distributor device 32, which is arrangedin the area of a second (in FIG. 1 on the right) front side of the gasguidance device 24 between the separating plates 26, 28. The distributordevices 30, 32 are respectively made of a corrosion-resistant materialsuch as CFC, silicon carbide, silicon nitride or a glass ceramicmaterial. In the present exemplary embodiment, the distributor devices30, 32 are in each case a plate which is equipped with a plurality ofvertical slits 33 which are in particular aligned with the substrates12. As an alternative or an addition, the plate, or each plate, can alsocontain a plurality of holes.

The upper and lower separating plate 26, 28, the first and seconddistributor device 30, 32 and if appropriate, also the front and rearseparating plate, not shown, form a housing for the substrates 12, whichis designed at least approximately with sealed gaps, so that a gas flow35 which flows through the gas guidance device 24 is guided in thehousing and cannot escape from it through the side.

In an upper chamber area 34 located between the upper separating plate26 and the processing chamber wall 16, a heating device 36 is arranged,for example a silicon carbide meander heating matrix, while in a lowerchamber area 38 located between the lower separating plate 28 and theprocessing chamber wall 16, a cooling device 40 is arranged, for examplea plate stack cooler or a tube bundle cooler. As an alternative, thecooling device 40 can be arranged in the upper chamber area 34 and theheating device 36 can be arranged in the lower chamber area 38, or theheating and cooling devices can be arranged on top of each other in theupper or lower chamber area (not shown). In the latter case, only oneseparating plate and one pair of gas deflection elements are required.The separating plate is then arranged between the heating and coolingdevice, and the gas deflection elements are arranged on the front sidesof the separating plate.

In the area of one end (in FIG. 1, the right end) of the heating device36, a gas inlet device 42 is arranged which extends through theprocessing chamber wall 16 and which makes it possible to feed aprocessing gas 44 into the processing chamber 14 from outside, in thepresent exemplary embodiment, a gas comprising an elementary selenium orsulphur vapor. Although the gas inlet device 42 can generally bearranged at any point on the processing chamber 14, the arrangementshown in FIG. 1 is particularly advantageous, since the processing gas44 which is guided through the gas inlet device 42 during normaloperation first flows through the heating device 36 and is thus heateddirectly after entering the processing chamber 14. The gas inlet device42 is connected via a feed line 100 to a source 102 for elementaryselenium vapor and to a source 104 for elementary sulphur vapor. Thesource 102 for elementary selenium vapor and the source 104 forelementary sulphur vapor is respectively assigned to a valve 106 or 108which is arranged in the feed line 100, which makes it possible toselectively switch on the source 102 for elementary selenium vapor orthe source 104 for elementary sulphur vapor, and thus to selectivelyfeed elementary selenium vapor and/or elementary sulphur vapor to theprocessing chamber 14.

The source 102 for elementary selenium vapor comprises an evacuablesource chamber 110, in which a crucible 114 is arranged which is filledwith melted selenium mass 112. Furthermore, the source 102 comprises aline 116 for a pre-heated inert carrier gas 118, such as nitrogen orargon. The pre-heating can be regulated in such a manner that thecarrier gas temperature does not fall below the crucible temperature.

In the exemplary embodiment shown, the line 116 is arranged in such amanner that the carrier gas 118 is guided through the melted seleniummass 112 according to the bubbler principle. However, alternatively, itwould also be possible to arrange the line 116 in such a manner that thecarrier gas is guided away over the surface of the melted selenium mass112. Ultimately, the most important factor in the configuration of thesource 102 is the fact that the carrier gas is guided through the source102 in such a manner that it transports vaporizing elementary seleniumvapor from the melted selenium mass 112 into the processing chamber 14.

In order to ensure sufficient vaporization of the elementary seleniumfrom the melted selenium mass 112, i.e. sufficient vapor pressure, themelted selenium mass 112 is maintained at a predetermined seleniumsource temperature by means of a heating device not shown.Alternatively, a temperature profile of the source can be run whichenables the selenium partial pressure progression required for theprocess.

As can be seen in the selenium vapor pressure curve shown in FIG. 2(curve a), significant vapor pressures greater than 1 ton (1 ton=1.3mbar) are only achieved with a selenium source temperature ofapproximately 360° C. and above. As will be explained in greater detailbelow, the selenization process can however be implemented under roughvacuum ambient pressure or overpressure conditions, e.g. with aprocessing chamber pressure or total pressure of at least 900 mbar.

With the exemplary embodiment presented, the necessary processingchamber pressure is primarily set by the pressure of the carrier gas118, which transports the selenium vapor into the processing chamber 14with a total pressure as the total of the carrier gas pressure and theselenium vapor pressure according to the source temperature. Forexample, with a total pressure of 900 mbar, the selenium partialpressure can be set to approximately 30 mbar (1 mbar=0.7501 Torr),whereby the selenium crucible temperature is set to approximately 450°C., the carrier gas is set to at least 450° C. and the temperature onthe inner surfaces of the processing chamber 14 and in particular on thesubstrates 12 at no point falls below 450° C., in order to preventselenium condensing out. The essential condition for a reproducibleprocess which can be controlled highly effectively, the avoidance of acondensing out of the processing vapors, can be particularlysuccessfully realised with the chamber arrangement according to theinvention when forced convection is used.

The source 104 for elementary sulphur vapor comprises a structure whichcorresponds to the source 102, i.e. the source 104 also comprises anevacuable source chamber 110′, in which a crucible 114′ is arranged,which in this case contains melted sulphur mass 120, however. In thepresent exemplary embodiment, the source 104 also comprises a line 116′,in order to guide pre-heated carrier gas 118, e.g. nitrogen, through themelted sulphur mass 120. As with the source 102, the line 116′ of thesource 104 can however also be arranged in such a manner that thecarrier gas is guided away over a surface of the melted sulphur mass120.

Furthermore, the melted sulphur mass 120 of the source 104 is maintainedat a predetermined source temperature by means of a heating device notshown, in order to ensure sufficient vaporization of elementary sulphurvapor or to ensure sufficient vapor pressure. Alternatively, atemperature profile of the source can also be run here, which enablesthe sulphur partial pressure progression required for the process.

As can be seen in the sulphur vapor pressure curve shown in FIG. 2(curve b), a vapor pressure of 30 mbar in the case of sulphur is alreadyachieved with a sulphur source temperature of approximately 280° C. andabove in contrast to selenium.

In a similar manner as with the source 102 for elementary seleniumvapor, it is also the case that with the source 104 for elementarysulphur vapor, according to the exemplary embodiment shown, thenecessary processing chamber pressure is primarily set by the pressureof the carrier gas 118, which transports the sulphur vapor into theprocessing chamber 14 with a total pressure as the total of the carriergas pressure and the sulphur vapor pressure according to the sourcetemperature.

In order to prevent the elementary selenium or sulphur vapor fromcondensing on the walls 122, 122′ of the source chambers 110, 110′, oron the wall of the feed line 100, the source chamber walls 122, 122′ andthe feed line 100 are respectively maintained at a predeterminedtemperature by means of a tempering device 124, 124′, 126. Here, thetemperatures of the gas inlet device 42, the feed line 100 and thesource chamber wall 122 should be at least as high as those of thecrucible 114 for elementary selenium vapor, and the temperatures of thefeed line 100 and the source chamber wall 122′ should be at least ashigh as those of the crucible 114′ for elementary sulphur vapor.

Additionally, the crucible 114, the source chamber wall 122, the valve106 and the line 116 of the source 102 comprise a material which remainsstable in selenium, while the crucible 114′, the source chamber wall122′, the valve 108 and the line 116′ of the source 104 comprise amaterial which remains stable in sulphur. Accordingly, the feed line 100and the gas inlet device 42 are also formed of a material which remainsstable in selenium and sulphur. The materials which remain stable canfor example be a ceramic, quartz, a corrosion-resistant special alloy ora metal or metal alloy coated with a corrosion-resistant layer. Theselenium and sulphur source and the feed and discharge lines areequipped with thermally insulating, gas-tight housings (not shown),which prevent selenium and sulphur from escaping should a breakage ofthe corrosion-resistant material occur. The space between the housingand these corrosion-resistant materials can e.g. be coated with nitrogenin order to prevent air from entering the processing chamber. In orderto monitor a potential leak at the selenium or sulphur source, thenitrogen coating can be pressure monitored.

As is shown in FIG. 1, in the area of the first front side of the gasguidance device 24, at least one first ventilator 46 is upstream of thefirst distribution device 30, which is driven by a first drive shaft 48which extends through the processing chamber wall 16. On the oppositeside of the gas guidance device 24, two second ventilators 50 arearranged in the area of the second distributor device 32, which aredriven by the second drive shafts 52 which extend through the processingchamber wall 16. However, the arrangement can also be designed withventilators on only one side, e.g. with ventilators 50.

Both the first and second ventilators 46, 50 and the first and seconddrive shafts 48, 52 are made of a corrosion-resistant material, such asa ceramic material, in particular silicon nitride or silicon carbide, ora material such as a metal or metal alloy which is covered with acorrosion-resistant coating. The first ventilators 46 are driven in sucha manner that they convey gas into the gas guidance device 24, while thesecond ventilators 50 are at the same time operated in such a mannerthat they convey the gas out of the gas guidance device 24. Due to theoperation of the ventilators 46, 50, a gas flow circuit is thusgenerated which in the view shown in FIG. 1 is oriented in acounter-clockwise direction. In other words, the processing gas 44 whichis introduced into the processing chamber 14 through the gas inletdevice 42 flows from right to left through the heating device 36, thendownwards and from left to right through the gas guidance device 24 andthen upwards and again from right to left through the heating device 36.

For additional control of the gas flow in the processing chamber 14, anupper pair of reversible gas deflection elements 54 and a lower pair ofreversible gas deflection elements 56 are provided. The upper gasdeflection elements 54 are arranged in such a manner that they canpermit, throttle or fully prevent the flow of processing gas 44 from thegas guidance device 24 into the upper chamber area 34, or from the upperchamber area 34 into the gas guidance device 24. The lower gasdeflection elements 56 are accordingly arranged in such a manner thatthey can permit, throttle or fully prevent the flow of processing gas 44from the gas guidance device 24 into the lower chamber area 38, or fromthe lower chamber area 38 into the gas guidance device 24.

In the situation shown in FIG. 1, the upper gas deflection elements 54are in an open position, so that a circulation of the processing gasthrough the upper area of the processing chamber 14, i.e. through thegas guidance device 24 and the heating device 36 is possible.

The lower gas deflection elements 56 are by contrast in a closedposition, i.e. they prevent a circulation of the processing gas 44through the lower area of the processing chamber 14 and in particularthrough the cooling device 40. Therefore, in the situation shown in FIG.1, only hot processing gas is circulating, which contributes to amaintenance of a required processing temperature, e.g. ranging from 400°C. to 600° C. If the upper gas deflection elements 54 are closed,however, and the lower gas deflection elements 56 are opened, theprocessing gas 44 flows through the cooling device 40, and thesubstrates 12 are cooled to a reduced temperature, e.g. 250° C.

In order to load the processing chamber 14, the processing device 10comprises on its front side a loading opening 60 which is embedded inthe processing chamber wall 16, which can be closed by a plate valve 62or another suitable door (FIG. 4).

The substrates 12 to be processed are arranged in a carrier 64, e.g. ona carriage supported on wheels, vertically oriented and at a distancefrom each other, in order to form a substrate stack 66, also known as abatch. The substrate stack 66 is conveyed through the loading opening 60into the processing chamber 14 and is placed in the gas guidance device24. After the loading opening 60 has been closed, the processing chamber14 is repeatedly evacuated and rinsed, in order to reduce as far aspossible the oxygen and water content in the processing chamber 14.

In order to evacuate the processing chamber 14, the processing chamberwall 16 is equipped with a suitable suction opening (not shown), towhich a pump system (also not shown) is connected. In order to rinse theprocessing chamber 14, a suitable gas inlet is provided in theprocessing chamber wall 16, through which a rinsing gas e.g. N₂, can beconveyed into the processing chamber 14.

As soon as the atmosphere in the processing chamber 14 comprises asuitable, defined initial state, the ventilators 46, 50 are switched on,the heating device 36 is activated and nitrogen gas is introduced intothe processing chamber 14. The upper gas deflection elements 54 are atthis point in time open and the lower gas deflection elements 56 areclosed, as is shown in FIG. 1, in order to enable heating of thesubstrates 12. At the same time, the selenium source is maintained at abasic temperature of e.g. between 150° C. and 300° C. (curve A in FIG.3).

As soon as the temperature in the processing chamber 14 has reached therequired reaction start temperature, e.g. between room temperature and400° C., and preferably between 150° C. and 300° C., the valve 106 whichis assigned to the source 102 for elementary selenium vapor is openedand the elementary selenium vapor which is mixed with the carrier gas118 is introduced into the processing chamber 14 through the gas inletdevice 42 as processing gas 44. Here, the condition is maintained that aselenium condensation is avoided on the substrates. This is achieved dueto the fact that the selenium partial pressure in the processing chamberdoes not exceed the selenium vapor pressure in accordance with the vaporpressure level at the current substrate temperature. Due to ameasurement of the carrier gas pressure and the carrier gas temperaturein the processing chamber before introducing the selenium vapor and dueto knowledge of the processing chamber volume and measurement of thesubstrate temperature, the carrier gas flow through the selenium sourceand the selenium crucible temperature, the selenium partial pressure inthe chamber can be determined e.g. by means of a computer, andtransferred to the regulation device for the selenium source. Thisdevice then adjusts the flow of carrier gas 118, the crucible, sourcewall and feed and discharge tube temperatures, taking into account thevapor pressure curve. A sufficient condition for avoiding seleniumcondensation is e.g. that the selenium source temperature (curve A inFIG. 3) is not greater than the temperature in the processing chamber14, and in particular is not greater than a minimum substratetemperature (curve B in FIG. 3).

In order to influence the strip distance of the I-III-VI connectingsemiconductor in a targeted manner, and as a result, to increase theefficiency of the solar module, in this phase, sulphur can already befed to the selenium flow by switching on the sulphur source in such amanner that preferably, a partial pressure ratio of sulphur to seleniumof greater than 0 and up to 0.9, preferably ranging from 0.1 to 0.3, iscreated. Here, the sulphur source is regulated in the same manner as theregulation of the selenium source described above. After the processinggas 44 has flowed away over the substrates 12 for a specific timeperiod, at a processing chamber pressure in the range of e.g. 100 mbarto ambient pressure, preferably between 700 mbar and 950 mbar, at arequired temperature profile (FIG. 3), a required gas flow speed and atthe required selenium or sulphur partial pressures, e.g. ranging from0.001 mbar to 100 mbar, the feed of elementary selenium and sulphurvapor is stopped, if necessary, the ventilators 46, 50 are shut down andthe processing chamber 14 is evacuated and/or rinsed at least once.Alternatively, only the feed of selenium vapor can be stopped. Duringthis process, the selenium source temperature is reduced back to itsinitial temperature of e.g. 150° C. to 300° C.

The valve 108 which is assigned to the source 104 for elementary sulphurvapor is opened, and the elementary sulphur vapor which is mixed withthe carrier gas 118 is conveyed into the processing chamber 14 asprocessing gas through the gas inlet device 42. In alternative operatingmode, the valve 108 remains open. At the same time, the ventilators 46,50 are switched back on, if they have previously been shut down. Theprocessing temperature is further increased, e.g. to between 400° C. and600° C., and is maintained at a set temperature for a specific timeperiod (FIG. 3).

With a processing chamber pressure in the rough vacuum, ambient pressureor overpressure range, the required gas flow speed and sulphurconcentration is regulated, with the latter ranging e.g. from 0.01 mbarto 100 mbar.

With this processing stage, the condition is also maintained that thesulphur partial pressure in the processing chamber does not exceed thesulphur vapor pressure with the corresponding substrate temperature, inorder to avoid sulphur condensation. The regulations and measures givenin the description for the selenium source also apply here. Here also, asufficient measure that the sulphur source temperature (curve C in FIG.3) is not greater than the temperature in the processing chamber 14, andin particular is not greater than a minimum substrate temperature (curveB in FIG. 3). The sulphur source temperature is for this purposemaintained or adjusted e.g. in the temperature range of between 100° C.and 450° C., preferably between 150° C. and 350° C.

After the heating procedure has been completed, the upper gas deflectionelements 54 are brought into their closed position, and the lower gasdeflection elements 56 are opened, so that the processing gas 44 is nowguided through the cooling device 40 and the substrates 12 are cooled toa temperature e.g. ranging from 350° C. to 150° C., such as 250° C.

After renewed pumping of the processing chamber 14 and filling withnitrogen, the processing of the substrate stack 66 is completed, so thatit can be removed from the processing chamber 14.

The heating and cooling rates, which can be achieved with the processingdevice 10 and which can be set in a broad range—e.g. from 5° C./min to600° C./min—make it possible to implement the processing of thesubstrate stack 66 in the processing chamber 14, i.e. in the presentexemplary embodiment, to selenise and sulphurise the metal-coated glasssubstrates 12 in less than 2 hours.

In general, it is possible to remove the processing goods stack 66through the loading opening 60 on the front side 58 of the processingdevice 10.

In the present exemplary embodiment, the processing device 10 compriseson its rear side 68 a discharge opening 70 which is embedded in theprocessing chamber wall 16, and which in a similar manner to the loadingopening 60 can be closed by a plate valve 72 or another suitable door(FIG. 4). The equipment of the processing device 10 with a loadingopening 60 and a discharge opening 70 which is located opposite has theadvantage that the processing device 10 is used as a through-flowdevice, and can be coupled with additional processing devices.

FIG. 5 shows a processing plant for example which comprises a processingdevice 10 and a cooling device 10′ which is connected on the outletside. The cooling device 10′ is designed in a similar manner to theprocessing device 10, with the single difference that the upper chamberarea 34 does not have the heating device 36 arranged inside it. Sincethe cooling device 10′ is solely provided to cool the glass substrates12, and a cooling gas, in particular an inert gas such as nitrogen gas,is solely designed to flow through the gas guidance device 24′ and thelower chamber area 38′ which comprises the cooling device 40′, the upperand lower gas deflection elements 54, 46 are also not present. For thepurpose of greater clarity, no second distributor devices 32 are shown.

The cooling device 10′ is coupled via a connection section 74 to theprocessing device 10 and is arranged next to said device in such amanner that a loading opening 60′ of the cooling device 10′ is alignedwith the discharge opening 70 of the processing device 10. The loadingopening 60′ of the cooling device 10′ can be opened and closed at thesame time by a plate valve 62′ with or independently of the dischargeopening 70 of the processing device 10.

Due to the arrangement of the processing device 10 and the coolingdevice 10′ in series, it is possible to move the processing goods stack66 after processing has been completed in the processing device 10through the discharge opening 70 and the discharge opening 60′ in thecooling device 74. The sluicing out of the processing goods stack 66from the processing device 10 into the cooling device 74 can for examplebe conducted at a temperature ranging from 400° C. to 200° C.,particularly from 300° C. to 250° C.

After the processing goods stack 66 has been conveyed into the coolingdevice 10′, the plate valve 72 is again closed and the processing device10 is fed a new processing goods stack 66.

At the same time, the first processing goods stack 66, which is nowlocated in the cooling device 10′, can be further cooled, e.g. to 80°C., wherein by actuating the ventilators 50′, circulating nitrogen gasis guided past on the glass substrates 12 and through the cooling device40′. After a final evacuation and final filling of the cooling device10′, the processing goods stack 66 can be removed from the coolingdevice 10′ through a discharge opening 70′. The cooling device 10′ isnow ready for retention of the next processing goods stack 66 from theprocessing device 10.

As is shown in FIG. 6, a sluice chamber 76 can be upstream of theprocessing device 10, which prevents ambient atmosphere from enteringthe processing chamber 14 during loading of the processing device 10with a processing goods stack 66. In the sluice chamber 76, theprocessing goods stack 66 can be pre-heated from room temperature to atemperature ranging from 100° C. to 200° C., e.g. approximately 150° C.

Furthermore, a transport mechanism for moving the carrier 64 whichsupports the processing goods stack 66 through the processing plant cancomprise an insertion mechanics system for inserting the carrier 64 andprocessing goods stack 66 from the sluice chamber 76 into the processingchamber 14, and a withdrawal mechanics system for withdrawing thecarrier 64 and processing goods stack 66 from the processing chamber 14into the cooling device 10′. In this manner, it can be prevented thatthe moved parts of the transport mechanism come into contact with thehot and corrosive areas of the processing plant.

FIG. 7 shows an alternative embodiment of a processing device 10according to the invention, which is e.g. provided for the formation ofCu(In, Ga)(Se, S)₂ semiconductor layers on substrates 12 which are to beused for the production of solar cells.

The processing device 10 comprises an evacuable processing chamber 14,which is limited by a processing chamber wall 16. The processing chamberwall 16 is formed from stainless steel and is maintained by a temperingdevice, which can be designed in a similar manner to the processingdevice shown in FIG. 1, at a temperature ranging from 150° C. to 250° C.Accordingly, this can be a tube line system, which is attached to theouter side of the processing chamber 14, and in particular welded to theprocessing chamber wall 16 and which encircles the processing chamber 14in a meander form, through which e.g. a suitable hot oil flows. As analternative or additionally, the hot oil can however also flow throughchannels (not shown) which are accordingly embedded into the processingwall 16. Additionally, the outer side of the processing chamber wall 16can be equipped with a thermally insulating material.

On an inner side of the processing chamber wall 16, the processingchamber 14 is at least approximately completely cladded with acorrosion-resistant, low-particle, thermal insulation material 22. Theinsulation material 22 can be a ceramic, a glass ceramic, graphite orgraphite foam, including a fibre material, e.g. Carbon Fibre EnforcedCarbon (CFC) or graphite felt, or an insulation material containingceramic fibres, e.g. consisting of SiO₂ and Al₂O₃ fibres.

A gas guidance device 24 is arranged in a central area of the processingchamber 14. The gas guidance device 24 comprises an upper separatingplate 26 and a lower separating plate 28. In addition to the upper andlower separating plate 26, 28, a front and a rear separating plate (notshown) can be provided. Generally, however, the front and rearseparating plate are not present, since their function is fulfilled bythe thermally insulated chamber side walls, including the doors orvacuum valves arranged there. The upper and lower separating plate 26,28 and if appropriate, the front and rear separating plate arepreferably formed from a corrosion-resistant material, such as CFC, froma ceramic material, such as silicon carbide or silicon nitride, or aglass ceramic material.

All separating plates are also cladded with a layer of the forenamedthermal insulation material 22.

The gas guidance device 24 furthermore comprises a first distributordevice 30, which is arranged in the area of a first (in FIG. 1 on theleft) front side of the gas guidance device 24 between the separatingplates 26, 28, and/or a second distributor device 32, which is arrangedin the area of a second (in FIG. 1 on the right) front side of the gasguidance device 24 between the separating plates 26, 28. The distributordevices 30, 32 are respectively made of a corrosion-resistant materialsuch as CFC, silicon carbide, silicon nitride or a glass ceramicmaterial. In the present exemplary embodiment, the distributor devices30, 32 are in each case a plate which is equipped with a plurality ofvertical slits 33 which are in particular aligned with the substrates12. As an alternative or an addition, the plate, or each plate, can alsocontain a plurality of holes.

The alternative embodiment 10 according to FIG. 7 furthermore contains asecond feed line 208, e.g. for selenium or sulphur, and if appropriate athird feed line for sulphur or selenium (not shown) as a component of atransfer device 200, via which selenium and/or sulphur first enter theprocessing chamber 14 in solid form. The third feed line respectively isthen a regular component of a separate supply and dosing unit. Here,solid selenium or solid sulphur can be stored, preferably under inertgas conditions, in the solid materials supply 202. Via the dosing device204, solid selenium or solid sulphur can be transferred via the secondfeed line 208 by actuating the valve 206 into a vaporization unit 210located inside the processing chamber 14. In other words, the valve isalso integrated into the feed line to the processing chamber. The inertgas feed line 216 opens out upstream of this valve 206. If the seleniumor sulphur are present in melted form in the crucible 210, according toa method variant, the valve 206 can be closed and the inert gas feed canbe increased via the feed line 216. In this manner, the quantity ofelementary selenium or sulphur vapor from the shuttle or crucible 210can be adjusted or increased. The solid material which is introduced inthis manner can for example be converted with the aid of a heatingelement 214 which is arranged below the crucible/shuttle into fluid andgaseous selenium or gaseous sulphur vapor, which can then be fed via agas distributor into the processing chamber 14 as elementary selenium orsulphur vapor 44. In order to ensure that the entire transfer processtakes place under inert conditions, inert gas can be introduced into thesecond feed line 208 via a feed line 216. This inert gas flow can beused to deliver selenium or sulphur vapor from the vaporization unit 10in a particularly effective manner.

The method according to the invention can be implemented in aparticularly secure manner using the processing device shown in FIG. 7.Additionally, the procedure made possible by this device has theadvantage that solid selenium or solid sulphur can be dosed in a highlyprecise manner. It is no longer necessary to open the processing devicefor the introduction of solid selenium or sulphur, and an externalvaporization source and the entailing apparatus costs are no longerrequired.

Instead of introducing the sulphur or selenium in solid form into theprocessing chamber via a feed line, or in a shuttle or crucible presentin the processing chamber, according to a further embodiment shown inFIG. 8, a processing device 10 can be provided in which one or moreshuttles filled with solid selenium or solid sulphur, if appropriatealso filled with fluid selenium or fluid sulphur, are inserted into theprocessing chamber 14 via a transfer station or transfer or sluicechamber 228. This advantageously occurs under inert gas conditions,using the vacuum feeders 222 and 224. In this embodiment, the transferor sluice chamber 228 is docked onto the processing chamber 14. In thevariant shown, a shuttle module 230 containing a plurality ofshuttles/crucibles 218 with selenium or sulphur pellets is filled via anexternal dosing device 234 from a corresponding supply 232 with the aidof a valve 236 (see FIG. 8 a). The filling stage of the shuttle module230 can already be implemented under inert conditions in a simplemanner. The filled shuttle module 230 is introduced into the transfer orsluice chamber 228 via the vacuum feeder 224 (FIG. 8 b). The shuttlemodule 230 can be prepared in the transfer or sluice chamber 228 forintroduction into the processing chamber 14 via the vacuum feeder 222 bymultiple evacuation and rinsing with inert gas. In the processingchamber 14, the selenium or sulphur present in the individual shuttles218 in solid form can be converted into a fluid state using the heatingunit 226 (FIG. 8 c). Via the inert gas feed line 220, inert gas entersthe respective shuttles 218 and forces the distribution of elementarysulphur or selenium vapor inside the processing chamber. The feed device220 can be designed in the form of a gas chamber, containing a pluralityof injection nozzles, for example. Alternatively or additionally, theelementary selenium or sulphur vapor can be discharged from therespective shuttle 218 by the ventilators 50 and distributed in theprocessing chamber 14. Furthermore, it is possible to go without theheating unit 226, since the heating device of the substrate in theprocessing chamber 14 ensures corresponding processing temperatureswhich lead to a fluidization of the selenium or sulphur. As a rule, theshuttle module 230 is retained in the processing chamber 14 until allsulphur or all selenium has been vaporised. The shuttle module 230 canthen be further conveyed out via the transfer or sluice chamber 228 andre-filled.

FIG. 9 shows a further development of the embodiment of a processingdevice 10 as shown in FIG. 8. Inert gas is fed into each shuttle via theinert gas feed line 220. As a result, the selenium or sulphur which hasbeen liquidized via the heating unit 214 is discharged from the outletnozzle 242 in elementary vapor form. Alternatively or additionally, theflow generated via the ventilators 50 can be used to transfer fluidizedselenium or fluidized sulphur into the processing chamber. This isachieved particularly effectively when a flow deflection device, whichcan in particular be pivoted or changed in its position, is provided, inparticular in the form of a flow flap valve 238, with the aid of whichthe gas flow in the processing chamber which is generated by theventilators 50 is guided in a targeted manner over the surface of thefluidized selenium or sulphur. In the embodiment shown in FIG. 9, theflow flap valve 238 guides the inert gas flow via the inlet opening 240over the fluid selenium or sulphur surface, so that via the outletopening or nozzle 242, elementary sulphur or elementary selenium can bedischarged in vapor form. Insofar as is necessary, the deflection plates54 can also be used to guide the gas flow over the fluid selenium orsulphur samples in the crucibles 218.

The features of the invention disclosed in the present description, inthe claims and in the drawings can be essential both individually and inany combination for the realization of the invention in its differentembodiments.

LIST OF REFERENCE NUMERALS

-   10 Processing device-   12 Substrate-   14 Processing chamber-   16 Processing chamber wall-   18 Tempering device-   20 Tube line-   22 Thermal insulation material-   24 Gas guidance device-   26 Upper separating plate-   28 Lower separating plate-   30 First distributor device-   32 Second distributor device-   33 Slit-   34 Upper chamber area-   35 Gas flow-   36 Heating device-   38 Lower chamber area-   40 Cooling device-   42 Gas inlet device-   44 Processing gas-   46 First ventilator-   48 First drive shaft-   50 Second ventilator-   52 Second drive shaft-   54 Upper gas deflection element-   56 Lower gas deflection element-   60 Loading opening-   62 Plate valve-   64 Carrier-   66 Processing goods stack-   68 Rear side-   70 Discharge opening-   72 Plate valve-   74 Connection section-   76 Sluice chamber-   100 Feed line-   102 Source for elementary selenium vapor-   104 Source for elementary sulphur vapor-   106 Valve-   108 Valve-   110 Source chamber-   112 Melted selenium mass-   114 Crucible-   116 Line-   118 Carrier gas-   120 Melted sulphur mass-   122 Source chamber wall-   124 Tempering device-   126 Tempering device-   200 Transfer device-   202 Solid material supply-   204 Dosing device-   206 Valve-   208 Feed line-   210 Vaporization unit-   214 Heating element-   218 Feed line-   218 Shuttle/crucible containing selenium or sulphur-   220 Inert gas feed line-   222 Vacuum feeder-   224 Vacuum feeder-   228 Heater for Vaporization unit-   228 Transfer chamber-   230 Shuttle module-   232 Selenium or sulphur solid material supply-   236 Dosing unit-   236 Valve-   238 Flow flap valve-   240 Flow inlet-   242 Flow outlet nozzle

1. A method for producing semiconductor layers and coated substratestreated with elemental selenium and/or sulphur, in particular flatsubstrates, containing at least one conducting, semiconducting and/orinsulating layer, in which a substrate which is provided with at leastone metal layer and/or with at least one layer containing metal, inparticular a stack of substrates, each of which is provided with atleast one metal layer and/or with at least one layer which containsmetal, is inserted into a processing chamber and heated to apredetermined substrate temperature; elementary selenium and/or sulphurvapor is guided past on the or on every metal layer and/or layercontaining metal, from a source located inside and/or outside theprocessing chamber, in particular by means of a carrier gas which is inparticular inert, under rough vacuum conditions or ambient pressureconditions or overpressure conditions, in order to react chemically withsaid layer with selenium or sulphur in a targeted manner; the substrateis heated by means of forced convection by at least one gas conveyingdevice and/or the elementary selenium and/or sulphur vapor is mixed andguided past on the substrate by means of forced convection by at leastone gas conveying device in the processing chamber, in particular in ahomogeneous manner.
 2. A method according to claim 1, wherein the gasconveying device comprises an injection nozzle or a ventilator.
 3. Amethod according to claim 1, wherein the gas conveying device, inparticular the ventilator, is preferably arranged in the area of one ofthe front sides of the processing goods stack, and/or is affixed to adrive shaft which extends into the processing chamber.
 4. A methodaccording to claim 1, wherein the in particular external source ismaintained at an increased source temperature or is adjusted to anincreased source temperature, which, at any point in time during theguiding past of the elementary selenium and/or sulphur vapor on thesubstrate, is preferably lower than the temperature in the processingchamber and in particular, lower than a minimum substrate temperature.5. A method according to claim 1, wherein a first feed line throughwhich the elementary selenium or sulphur vapor is guided on the routefrom the first, in particular external, source to the substrate, and/ora wall which defines the processing chamber is maintained at atemperature which is equal to or greater than the temperature of the, inparticular external, source.
 6. A method according to claim 1, whereinas an in particular external source, a bubbler comprising fluid seleniumor fluid sulphur through which the carrier gas is guided can be used asa source, or a crucible filled with fluid selenium or sulphur can beused which comprises a side which enables the selenium or sulphur toevaporate, and on which the carrier gas is guided past.
 7. A methodaccording to claim 1, wherein the chemical reaction of the seleniumand/or the sulphur with the metal layer and/or the layer containingmetal is conducted under a total pressure in the processing chamber inthe range of rough vacuum conditions or ambient pressure conditions oroverpressure conditions and/or under a selenium or sulphur vapor partialpressure ranging from approximately 0.001 mbar to approximately 100mbar.
 8. A method according to claim 1, wherein the metal layer or layercontaining metal comprises at least the elements In, Cu, and/or Ga.
 9. Amethod according to claim 1, further comprising the following stages:(a) Increase of the substrate temperature with a heating rate ofapproximately 5° C./min to 600° C./min, preferably 10° C./min to 60°C./10 mins, from a first temperature, in particular room temperature, toa temperature ranging from approximately 400° C. to 600° C., preferably400° C. to 500° C.; (b) Feeding of elementary selenium vapor into theprocessing chamber from a substrate temperature ranging from 100° C. to350° C., in particular between 120° C. and 300° C., if appropriate,followed by the feeding of elementary sulphur vapor into the processingchamber, and here, if appropriate, the subsequent adjustment of theselenium source temperature to a required partial pressure, preferablybetween 0.001 mbar and 100 mbar; (c) Maintenance of the substratetemperature in a range from 400° C. to 600° C. for 1 min to 120 mins,preferably for 10 mins to 30 mins; (d) While maintaining the substratetemperature in a range from 400° C. to 600° C., shutdown of the feed ofelementary selenium vapor, and if appropriate, of sulphur vapor into theprocessing chamber after a first predetermined time period, inparticular after a time period of between 1 and 120 mins, preferablybetween 1 and 60 mins; (e) At least a one-time pumping out and/orrinsing of the processing chamber, in particular with at least one inertgas; (f) Feeding of elementary sulphur vapor into the processingchamber; (g) Continued increase of the substrate temperature with aheating rate of approximately 50° C./min to 600° C./min, preferably 10°C./min to 60° C./min, to a temperature ranging from approximately 450°C. to 650° C., preferably 500° C. to 550° C., and during this procedure,if appropriate, an adjustment of the sulphur source temperature to arequired partial pressure, preferably between 0.001 mbar and 100 mbar;(h) Maintenance of the substrate temperature in a range from 450° C. to650° C. for 1 min to 120 mins, preferably for 1 to 60 mins, andparticularly preferably for 10 mins to 30 mins; (i) While maintainingthe substrate temperature in a range from 450° C. to 650° C., shutdownof the feed of elementary sulphur vapor into the processing chamberafter a second predetermined time period, in particular after a timeperiod of between 1 and 120 mins, preferably between 1 and 60 mins; (j)Cooling of the substrate; and (k) Pumping out and/or rinsing of theprocessing chamber, in particular with at least one inert gas.
 10. Amethod according to claim 1, wherein in a first stage, elementaryselenium vapor is guided past on the or each metallic layer and/or layercontaining metal (selenization stage), and that in a subsequent stage,elementary sulphur is guided past on the or each metal layer and/orlayer containing metal (sulphurization stage).
 11. A method according toclaim 1, wherein during the selenization stage, e.g., from a substratetemperature of between 120° C. and 600° C., elementary sulphur vapor isfed into the processing chamber, in particular in such a manner that apartial pressure ratio of selenium to sulphur is created between 0 and0.9, or preferably of sulphur to selenium ranging from above 0 to 0.9,preferably between 0.1 and 0.3.
 12. A method according to claim 1,wherein at least one reactive gas, in particular H₂Se, H₂S and/orhydrogen, is added to the carrier gas containing selenium and/or sulphurvapor.
 13. A method according to claim 1 wherein the metal layer orlayer containing metal comprises at least one of the elements In, Zn, orMg, and/or the semiconductor layer to be produced is a buffer layer, inparticular an In₂S₃—, In₂(S,Se)₃—, ZnSe—, ZnS—, Zn(S,OH)—, (ZnMg)S layeror an (In₂S₃—ZnS) mixed layer.
 14. A method according to claim 13,wherein the metal layer In and/or the layer containing metal contains anindium-sulphur compound and/or an indium-selenium compound, or consistsof these, or the buffer layer comprises an In₂S₃ layer or an In₂(S, Se)₃layer or consists of such a layer.
 15. A method according to claim 13,wherein the substrate temperature is lower than or equal to 350° C.,preferably lower than or equal to 250° C. and/or is preferably greaterthan 150° C., particularly preferably greater than or equal to 160° C.16. A method according to claim 1, wherein selenium and/or sulphur isinserted in solid form into the processing chamber via a transferdevice.
 17. A method according to claim 16, wherein the transfer deviceis a second feed line or a sluice chamber.
 18. A method according toclaim 17, wherein pre-heated carrier gas is fed via the second and/or atleast one third feed line to the internal selenium and/or sulphursource.
 19. A method according to claim 1, wherein the coated, inparticular planar substrates, in particular pre-coated glass substrates,can be used for the production of semiconductor layers, preferablychalcopyrite semiconductor layers, preferably I-III-VI connectionsemiconductor layers and in particular Cu(In, Ga)(Se,S)₂ semiconductorlayers, and/or buffer layers on I-III-VI connection semiconductorlayers, in particular In₂S₃,—, In₂(S,Se)₃ layers or (In₂S₃—ZnS) mixedlayers, in particular for solar cells.
 20. A method according to claim1, wherein H₂Se and/or H₂S can be added before and/or during theselenization stage with elementary selenium, in particular attemperatures ranging from room temperature to 350° C., preferably attemperatures ranging from 100° C. to 300° C.
 21. A method according toclaim 1, wherein the layer which contains metal comprises (i) at leastone metal and one non-metallic element of the periodic table ofelements, in particular sulphur and/or selenium, chlorine, or oxygen,and/or (ii) at least one chemical compound of a metal with anon-metallic element of the periodic table of elements, in particularsulphur and/or selenium, chlorine, or oxygen.
 22. A processing devicefor implementing a method according to claim 1, comprising: an evacuableprocessing chamber for receiving at least one substrate to be processed,in particular a stack of substrates to be processed; a heating devicefor the in particular convective heating of the substrate to beprocessed; a first source for elementary selenium and/or sulphur vaporlocated outside the processing chamber and which is connected to theprocessing chamber via a first feed line and/or a second source forelementary selenium and/or sulphur vapor located inside the processingchamber; and a gas conveying device for generating a gas flow circuit,in particular by means of forced convection in the processing chamber.23. A processing device according to claim 22, wherein the gas conveyingdevice comprises an injection nozzle or a ventilator.
 24. A processingdevice according to claim 22, wherein the gas conveying device, inparticular at least one ventilator, is arranged or arrangeable in thearea of one of the front sides of the substrate stack.
 25. A processingdevice according to claim 22, further comprising a tempering device, inorder to maintain at a predetermined temperature at least one partialsection of a wall which defines the processing chamber, in particularthe entire wall, and if appropriate, at least one section of the feedline respectively.
 26. A device according to claim 22, wherein the firstsource comprises a heatable and evacuable source chamber, in which acrucible filled with melted selenium or sulphur mass is arranged orarrangeable, and a line for in particular pre-heated carrier gas, insuch a manner that the carrier gas is either guided through or can beguided through the melted selenium or sulphur mass according to thebubbler principle, or is guided away from or can be guided away from themelted selenium or sulphur mass, wherein the crucible and the linepreferably comprise material which remains stable in selenium orsulphur, and in particular are formed from ceramic, quartz, orcorrosion-resistant special alloys or metals with corrosion-resistantcoatings.
 27. A device according to claim 22, wherein the heating deviceis arranged or arrangeable in the gas flow circuit generated by the gasconveying device, in order to heat a gas located in the processingchamber; and/or a cooling device for cooling down a gas located in theprocessing chamber is arranged or arrangeable in the gas flow circuitgenerated by the gas conveying device; and/or gas diversion elements areprovided through which the gas flow circuit can be diverted in such amanner that either the heating device or a cooling device is arranged orarrangeable in the gas flow circuit.
 28. A device according to claim 22,further comprising at least one device for the pre-dosing of solidselenium and/or solid sulphur outside the processing chamber, and/or atleast one device for transferring solid selenium and/or solid sulphurinto the processing chamber.
 29. A device according to claim 28, whereinthe transfer device comprises a second feed line and/or a sluicechamber, in particular containing a retaining device for solid seleniumor solid sulphur.
 30. A device according to claim 22, further comprisingat least one flow deflection device, which can in particular be pivotedor changed in its position, is provided, in particular in the form of aflow flap valve for the targeted guidance of inert gas, in particular ina retaining device, over the surface of the fluid or fluidized seleniumand/or fluid or fluidized sulphur located in the processing chamber. 31.A processing plant for processing stacked substrates with at least oneprocessing device according to claim 22, wherein the processing devicecomprises a loading opening, through which the substrate stack can beinserted into the processing chamber, and a discharge opening, throughwhich the substrate stack can be removed from the processing chamber.